im no hero x wrote:
It depends on which engine you've got...
Low n' slow is usually the way to go with mk4 Jettas and Golfs/GTIs.
The best part of owning a VW is the community though. Check out vwvortex.com (lots of a-holes in the mk4 forums, I should warn you lol) and come out to some shows and gtg's.

i agree with rich! vwvortex is full of aholes, try audizine, i know its an Audi forum, but many motors cross ways when it comes to VW and Audi...
1.8Ts are great motor BTW